Exploring The Science Of Flying, From Your Window Seat

This holiday season I'm sure is finding many of us on airplanes, flying around the country. It could take tedious hours of body scans, the crummy back-of-the-seat TV and scary airplane bumps and noises. But if you marvel at nature and technology, though, you can turn this torturous event into a more enjoyable learning experience.

My next guest has written a book about all the technology that goes into airline travel and the interesting stuff, and there really is, and I can tell you from personal experience, there really is a lot of interesting stuff going on, and you can hear it, you can see it from your window seat, like the wings flapping.

Have you ever watched the wings flapping, and you get scared? Well, don't worry, they are engineered to do that and not to fall off, and that's one of the things you'll learn in this new book by Brian Clegg. He's a science writer and author of "Inflight Science: A Guide to the World From Your Airplane Window." He joins us from Swindon, England. Welcome to SCIENCE FRIDAY.

BRIAN CLEGG: Hi there.

FLATOW: That's what a lot of people worry about, Brian Clegg, that those wings are going to fall off, right?

CLEGG: That's right, but in fact they're tested to such incredible tolerances, you can push these wings up on a modern plane, you know, through feet, yards even, out of their normal position, and they'll just spring back.

They're actually designed, as you say, to flap around a little as you fly because that means they're not taking so much stress. If they were actually totally rigid, they're much more likely to snap off. It'll actually keep you safe.

FLATOW: It's better to flap than break off.

CLEGG: Yeah,

FLATOW: Well, how did you get interested in this topic?

CLEGG: Well, I used to work for an airline. I worked for British Airways for - getting on for 20 years, and obviously there I did a lot of flying, but my background originally is in physics. And it was just a great opportunity to look at all the science that's around you when you're on a flight.

FLATOW: And let's talk about - we have to take a break, but before we go, let's talk about one thing that, you know, that's enjoyable. In the first part of your flight, you're on the runway, and you look out the window, and you see the runway has numbers on it. Do those numbers mean something?

CLEGG: Well, that's right. There at the ends of the runway, it's most obvious, maybe, when you're coming in to land, but these numbers just indicate the direction the runway is in. If you imagine sort of like a 360-degree clock, then you just take the first two numbers of the degrees, so say 100 degrees would be 10, 200 degrees would be 20 or whatever, and the numbers on the runway basically indicate the direction that the runway is pointing in.

FLATOW: Wow. 1-800-989-8255 if you'd like to talk about the science of flight, the technology, what those wacky noises you hear coming out from under the wings, or the flaps, and all kinds of stuff like that. You can also tweet us, @scifri. Talking with Brian Clegg, author of "Inflight Science: A Guide to the World from Your Airplane Window."

And some of the stuff you can see out of the window, on the ground. We'll talk about what there is to see. So your flight doesn't have to be so terrible this holiday season. Stay with us. We'll be right back after this break.

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FLATOW: I'm Ira Flatow. This is SCIENCE FRIDAY from NPR.

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FLATOW: I'm Ira Flatow. You're listening to SCIENCE FRIDAY. We're talking with Brian Clegg, author of "Inflight Science: A Guide to the World from Your Airplane Window." Our number, 1-800-989-8255. So we started talking about the runway, taking off, and you can learn your compass direction by adding a zero to the runway number, and that'll be the direction you're taking off.

And how long is the runway? Why - how long do runways have to be, Brian?

CLEGG: It depends, obviously, on the plane you're dealing with. We are talking a significant size with a modern plane. In fact, if you think about it, the way planes have come on over the years, it is quite incredible. Something I like to compare is if you look back to the Wright brothers, I don't know if you've ever seen the Wright brothers flyer in the Air and Space Museum, but the size of the entire flight that the Wright brothers took, originally, is actually shorter than the wingspan of a 747.

And to get a 747 off the ground, we're talking about a runway that has to be, you know, a significant length. I have to say I don't have the absolutely specific numbers in my head, but I think it's interesting that we've had examples in the past of planes that have actually landed on a runway that was too short for them and then couldn't take off because the length of the runway, you need a longer runway to be able to take off than you do to be able to land.

And in the early days at Heathrow, we had an American 707 that landed at another airport. They thought it was Heathrow, they landed at the wrong airport, and the runways were just too short to get off.

FLATOW: Still sitting there?

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CLEGG: Well, no, what they did is the stripped absolutely everything out of the plane to try to get it off. They took all the seats out. They took anything with weight out. And the legend is - I've never actually seen these - but one of the buildings near the runway, there are actually tire marks on the roof because it was so close.

FLATOW: Oh, no kidding.

CLEGG: We're talking really, you know, up to three miles long, a modern runway has to be.

FLATOW: Well, speaking of the weight, you have a story about coins in your book, About the weight on the plane and how important that they didn't think it was, but tell us that story.

CLEGG: Well, that's right. This is really about the weight of passengers. If they had their way, airlines would love to weigh passengers as they get on the planes, but it would be too embarrassing. In fact, they actually used to do it in the very early days of flight. And we just have to then estimate how much passengers are going to weigh, and on the whole, that works pretty well.

But occasionally, you'll get something that goes a little wrong, and this was a true story. It happened taking off from a German airport. The plane was taking off for a city that had a coin fair on, and a lot of the passengers on the plane were coin dealers, and their favorite coins they didn't want to put in the baggage in the old, they wanted it on their person.

So they all weighed more than usual because they had their pockets full of coins, and they literally had trouble getting this plane off of the runway. They only just got it off. It counted as an air incident that was basically caused by these coins.

FLATOW: Wow, here's a tweet coming in from Eve(ph). She says: I love turbulence, but I notice it frightens some people. Please let them know it won't break the plane in half.

CLEGG: That's right. There have been no modern airliners ever brought down by turbulence, small planes yes, occasionally, but a modern airliner, a modern big airplane is not going to be brought down due to turbulence.

It's not totally trivial. I mean, it is important to strap in, put your seatbelt on when they tell you to because there is a risk, if there's a lot of turbulence, that you might hit your head on the ceiling or something of that kind. But in terms of actually damaging the plane, you can regard it as going on a rollercoaster ride, you know, sit back and enjoy it.

What great things, if you look out your window, and you look at the ground, what interesting things can you try to pick out? Well, obviously when you're low, you've got some great opportunities to see things you don't normally see. So when you're taking off, when you're landing, it really is a great opportunity to look out there.

In the nighttime, one little thing you can do is just have a go at estimating the size of the town or city that you're over from the number of streetlights, which, you know, you can get an idea of the streetlights that are down there. But obviously, you can see things like coastlines in a way that you wouldn't normally see them. There's a really good opportunity to see all kinds of things.

One thing is that old buildings, archeology is essentially being done sometimes from the air because sometimes when you're low down in a plane, you can actually see the pattern in the crops or where buildings used to be, and you can pick out a building you just can't see from the ground. So you can actually discover ancient buildings that you just can't see at all from the ground and things like that.

So it really is worth, you know, getting over the, oh, I've done it so many times, I'm fed up with it, and looking at it with fresh eyes.

FLATOW: Especially if you fly over a big city, and you get to see, you know, New York or San Francisco or London. You know, people pay 100 bucks to take a helicopter ride just to look at the city, and you're flying over it, well, you've already paid for your fare for a freebie.

CLEGG: Well, that's right, and so many people spend their time, you know, glued to the in-flight entertainment, which is fine, but you really ought to take a look out the window and see what's out there.

JERRY: First I'd like to give a shout-out to your guest, since he's from Swindon, to the best band in the world from Swindon, XTC. And - but then my question was: Your guest had mentioned a pilot landing at the wrong airport. And I guess that just brought up the question in my mind is how much do the pilots pay attention to looking at the ground and what they see or how much do they rely on GPS or how much has that changed, where they're going and how their path takes?

FLATOW: Good question: Is GPS basically the basic navigation system now?

CLEGG: It is, but it's not the only one. I mean, when that thing happened, we're going back to the 1960s. Back then, they relied a lot more on eye and what you could see out of the window. And as it happened, there was a structure on the approach to Heathrow that was very similar to another structure on the approach to this little airport called Norfolk.

And what they ended up doing in the end was painting on large letters to say this one is the Heathrow one, effectively, so the pilots used it correctly. But these days, yes GPS will be one of the main things that are used, but planes also use what's called inertial navigation, which basically makes use of how the plane turns and twists and effectively keeps track of where you're going from the way the plane turns.

And that's kind of important because just occasionally, you might lose the GPS, you might have a problem with the GPS, and you've got the backup then. You've also got radio beacons that are used for navigation. So the whole spate of systems that are in there that weren't used so effectively back in the 1960s.

FLATOW: But could you basically say that on a long flight, you know, a few hours at a high altitude, that pilots have turned on an autopilot and are flying that instead of sitting there for hours at a time?

CLEGG: Well, there's an element of that, but I think what you have to remember is that, you know, they are involved in this. They're up there on the flight, and they're going to be making sure that things are safe. So yes, a fair amount of a flight these days can be done on autopilot, but at the same time, they will be checking out, always keeping an eye on the instruments and also obviously looking for other planes that might be in the area, things of that kind.

FLATOW: Let's go to Margie(ph) in Columbus, Ohio. Hi, Margie.

MARGIE: Hey, thanks for having me.

FLATOW: Go ahead, please.

MARGIE: Here's my question. I had the pleasure of working on the B1 Bomber program at Rockwell in the mid-'80s, and back then, all the old engineers that taught us young pups everything said there's a 15-second rule. And I want to see what you - if you agree with this.

The first 15 seconds and last 15 seconds are the most dangerous of the flight. So theoretically, if you make it to 15 seconds off the ground, a plane is supposed to be able to glide, so you lose the engines. A plane should be able to glide safely back to the runway.

I wonder if that's true. I've told many people that story, and one of my friends holds other people's hands and counts every time she's on a plane.

CLEGG: OK, I want to say, by the way, I saw a B1 coming into - we had one come into Heathrow when I was working there, and they are amazing-looking planes. Excuse me, but...

FLATOW: Fifteen seconds...

CLEGG: Essentially, it's true that the first part of a flight, the last part of the flight, the first, I mean, 15 second, 30 seconds, I wouldn't say it's exactly down to 15 seconds but the first - certainly within the first minute of a flight, the last minute of a flight is the most dangerous.

It's not really the case of once you pass that, you can just glide down safely. I mean, a modern airliner does not glide particularly well because they're incredibly - a fully loaded 747 is 400 tons, and that isn't going to glide pretty well. But the fact is you are in the most dangerous period there because you have very little time to correct problems.

When you're further up, you've got time to sort things out. You know, if an engine stalls, you've got time to restart it.

FLATOW: So the higher you are, the safer you are?

CLEGG: Yeah, absolutely.

FLATOW: Most people are afraid of the height, but the higher you are, you're actually safer up there.

CLEGG: Definitely.

FLATOW: Thanks, Margie. 1-800-989-8255 is our number. Lots of people would like to talk about - let's talk about on the approach and the landing, all these different sounds and noises start happening. And give us a progression of the first noises you might hear as you're approaching the landing, and what's going on there.

CLEGG: I think the thing to be aware of, you know, is that there are mechanical things happening out on the plane, so there will be noises. You have to expect that. The first thing, typically, that's going to happen is - particularly, if it's a night, they're going to turn the lights down, and they do that so that your eyes can get used to it being relatively dark. So if you had to evacuate the plane for any reason, which, of course, is very unusual, then you would have better nighttime vision.

You will hear things like the flaps starting to go out. So basically these extend the surface area of the wing. And the idea of that is it makes it possible to fly at a lower speed, because obviously you don't want to land at a full cruising speed. A 747, you're cruising at over 500 miles an hour. You want to get it down. And by extending the wings, you make it - it has more drag, so it's not so good for flying when you're cruising. But when you're slowing down, when you want to be landing, you'll hear those flaps going out. If you look out the window, you can actually see them effectively extending the back end of the wing. They make quite a lot of noise.

The other thing that makes a lot of noise is the undercarriage going down. So you could hear the doors opening, the wheels coming down and locking into place. That all does make quite a bit of noise. And then, of course, as you come down onto the ground itself, you had that little bump, a little screech from the tires, but then you'll get a roar from the engines, usually they're going into reverse thrust. So it's pushing backwards on the plane. And one of the interesting things about planes is that there's loads of physics in there. All your Newton's Third Law and things like that starts coming into it.

And the engines start operating effectively in the opposite direction, basically just by shoving a screen behind them that sends the blast that's going out of the back of them forwards; that helps slow down the plane. But again, it can sound a little scary but it's not.

FLATOW: Let's go get some more call. This one from Thomas in Bettendorf, Iowa. Hi, Tom.

TOM: Hi, thanks for taking my call. My wife and I take the trip to New Zealand, that long trek, every couple of years, and I notice the air speed differs from ground speed. And I was just wondering if you can explain the difference between the two.

FLATOW: Good question.

CLEGG: It's an excellent question, yeah, because it's something that's really important and useful. Basically, a plane is flying through air. And the thing that keeps it up out there is the air itself, it's the air moving over the wings. And so what you're interested in in terms of flying is the air speed, how fast you're moving with respect to the air around you. Now, often there are winds up there. If, for instance, you cross across the Atlantic, between America and Europe, there's really powerful winds up there that can be going as much as 200, 250 miles an hour. And I've been on a 747 crossing the Atlantic where we've actually gone faster than the speed of sound compared with the ground because we're being pushed along by that air.

So basically the difference between the air speed and the ground speed - the ground speed is just how fast you're going over the ground, how fast you're traveling. The air speed is how fast you're traveling with respect to the air. If the air is going in the opposite direction (unintelligible) the two speeds add together, and the result is effectively you go through that air faster.

FLATOW: Talking with Brian Clegg, author of "Inflight Science: A Guide to the World from Your Airplane Window" on SCIENCE FRIDAY from NPR. Of course, if you have that as a headwind, 215 (unintelligible), your ground speed is going to go way down, take you much longer to get there...

CLEGG: That's right.

FLATOW: ...cause you have to fight that wind, right?

CLEGG: That's right. And you'll find, you know, the time to cross the Atlantic differs - can differ by an hour or two depending upon the direction you're going in. So if you've got those winds with you, obviously what they do going the other way is they don't get into the jet stream, which is what those sort of high-speed winds are called in that particular area. They try to avoid that as much as possible so they don't get that as a headwind. You don't want to have a fight against that; it only operates at a certain height.

FLATOW: One really interesting thing you can see from an airplane that you can't see from the ground is a rainbow that's a full circle.

CLEGG: That's right. Naturally, a rainbow is a circle because basically it's coming from a drop of water or set of drops of water. And what it's doing is the drop of water is acting like a prism; it's turning the white light into a rainbow of colors, and that should be circular, around - effectively coming from around the whole drop. But in practice we don't see that because effectively the Earth gets in the way. But when you're up in the sky, you can actually see a whole circle of a rainbow. (Unintelligible) really impressive as you're over clouds because what tends to happen, because you have to have the sun behind you to cause a rainbow, you can actually see a shadow of your plane flying in the middle of the rainbow of the clouds. It looks quite stunning.

FLATOW: Yeah. I have seen that once. 1-800-989-8255. Let's go to John in Grants Pass, Oregon. Hi, John.

JOHN: Hi. You know, from the ground looking across San Francisco Bay, it sometimes looks like there's a massive amount of fog out there. I was flying out of San Francisco, was able to look down; the entire Pacific Coast was covered in fog, but the Golden Gate provided a notch. And a thin stream of fog came across the bay and impacted the El Cerrito Hills. So from the ground it would have look like a massive fog bank. But from the air you can see it was just a narrow stream pushed through the Golden Gate and across the bay, like a little curtain.

FLATOW: Yeah, it's great stuff that you - thanks for that tip. There's great stuff you can see from air, that you think you're in the middle of a cloud, and the cloud has a height to it.

CLEGG: That's right. And clouds you can experience in a totally different way when you're up in a plane. Seeing them from above, far from anything else, I think they can look much more impressive. And one of the things about clouds that I came across researching this book, which I think is really kind of neat, is the whole business of cloud nine. I don't know if you've come across this. But basically the idea that if you're on cloud nine, you know, you're happy, you're on top of the world, this was because, originally, there were nine types of cloud in the international classifications of clouds, and they actually added one to make 10.

So briefly, it was actually cloud 10 that was the highest one. But unusual in science, they decided to be romantic, so they renumbered them. So they went from naught to nine instead of one to 10. So cloud nine was still the highest you could be. You are still on top of the world if you're on cloud nine, which I think is rather nice.

FLATOW: What a great story. We're going to take a break right now. Our number, 1-800-989-8255, talking with Brian Clegg, "Inflight Science: A Guide to the World from Your Airplane Window." A great read this holiday to take along with you and into the plane and figure out what's going on there and all the physics about flight and atmosphere and the Earth.

Our number, 1-800-989-8255. You can tweet us, @scifri, @S-C-I-F-R-I. We'll come back and talk more with Brian. We're also going to talk about the questions we've asked before. Why do you have to turn off all those electronic devices on your plane? We've got some interesting answers, so we'll talk about that when we get back. So stay with us.

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FLATOW: You're listening to SCIENCE FRIDAY. I'm Ira Flatow.

We're ending up this hour talking about the science of flight with - talking with my guest, Brian Clegg, author of "Inflight Science." Last month, we had the MythBusters on. We talked about cell phones on airplanes, and the MythBusters tried this out, and they concluded this myth - that cell phones do not interfere with airplane navigation systems. But they couldn't get the FAA to let them try an experiment. They wanted to experiment on the airplane. The FAA said no way, you're not going to do that.

Well, someone else has been looking into this. Joining me now is Nick Bilton. He's a lead writer of the Bits blog and a columnist at The New York Times. He's done some of his own investigating into this. He joins us from San Francisco. Welcome to SCIENCE FRIDAY, Nick.

NICK BILTON: Thanks for having me on.

FLATOW: So what is with all these electronic devices? You've looked into it. What have you concluded?

BILTON: Well, you know, one of the things, I think, that's happened is recently we've had more and more incidents of people that have been frustrated when they can't use their Kindles and iPads in airplane mode while they're, you know, taxiing to - on the runway or when they're taking off or actually on descent.

And, you know, we had an incident last week where Alec Baldwin was, of course, kicked off a plane for playing "Words with Friends" as that flight was delayed. And I've been looking into it recently, and a lot of the rules that apply to the devices that we now - a lot of people use to read content, the rules that were set in place, actually these devices didn't even exist at the time. So there's a lot of curiosities of why these rules still exist, and I don't think the FAA really can answer these questions yet.

FLATOW: We heard this week that pilots are going to be allowed to use iPads...

BILTON: Yeah.

FLATOW: ...in the cockpit.

BILTON: Yes. So the first - actually, ironically, the flight that Alec Baldwin was kicked off was an American Airlines flight, and American Airlines is actually the first airline that is going to be allowing pilots to use iPads instead of flight manuals in the cockpit. And, you know, American Airlines said they've done extensive testing, and the FAA approved it based on this testing.

But the reality is they're doing exactly what passengers wanted to be doing. And, you know, no one's really - I mean, there probably are people that are arguing for this, but no one's really arguing to be able to have a conversation on their cell phone during takeoff and landing. I think people just want to be able to actually read devices...

FLATOW: Yeah. And if you don't want people to use an iPad with a Wi-Fi, turn the Wi-Fi off on the plane.

BILTON: Well, exactly. And, you know, some of the rules that exist, it's really strange. So one of the things that the FAA requires is that we shut down our devices...

FLATOW: Right.

BILTON: ...and then restart them when we reach 10,000 feet. And that rule is actually - it's causing more trouble than they actually really understand because what happens when you restart one of these devices - a lot of the devices we have today - iPhones, iPads and so on - they're not designed to be shut down. They're designed to just go to sleep when you press a little button that tells them to do that.

And when you shut these things down and they restart, they actually flood the entire device with a lot of electricity that hits every single sensor. And the electromagnetic interference that comes from that is much more drastic than if you had a device that was just turned on in airplane mode during takeoff and landing.

FLATOW: Mm-hmm. And is it a fact that Air Force One on the president's plane, no one is asked to turn off their devices for anything?

BILTON: Yes. So I wrote this column a couple of weeks ago saying, you know, that these rules don't make sense for the devices that we use on a daily basis today. And I got, you know, several people, reporters that I work with and from other organizations that said that they, you know, were on Air Force One, and they were never asked to turn off any device. And people were actually on their cell phones during takeoff and landing, and the Secret Service never required anyone to do that.

And so if, you know, the plane and the Secret Service that carries the president is - the people are allowed to use these devices, well, why can't passengers on regular airlines? And people that I've spoken to, you know, pilots, have said that, you know, they don't even actually understand why the rules exist when it comes to devices that can be turned into airplane mode.

FLATOW: Brian Clegg, did you discover anything at all in your research, doing the book on "Inflight Science" about this?

CLEGG: Well, I think the problem is that we lump everything together. The fact is a cell phone is totally different from something like a Kindle or an iPad in terms of its potential for causing any problems at all. I mean, there is a small possibility for a cell phone to cause a problem because basically it's a radio transmitter.

I was actually told, before coming on this radio program, have you got a cell phone near the phone? Turn it off if you have because it could cause interference, and that's the same worry. Basically, a radio transmitter causes electricity to flow in cables, and there is a very small possibility that could genuinely cause a problem. So I can understand why the cell phones.

As far as the other electronic devices, e-book readers, there really is no reason at all why they shouldn't be used. I can see with MP3 players, maybe they don't want people to have their iPod earphones in while they're doing the flight briefing and safety briefing, that kind of thing. So maybe there's a kind of excuse there.

And the other thing I've seen said is, with something like a laptop, maybe you don't want people having those loose and handy during takeoff and landing because if you did get in a situation where you get a lot of acceleration, like a crash situation, then they could turn into missiles, effectively. You don't really want to be hit on the back of the head by a 100-mile-an-hour laptop, which I can kind of understand.

FLATOW: Yeah. Let me get a quick call in...

CLEGG: (unintelligible) at all.

FLATOW: Let me get a quick call in from Matt in Salt Lake. Hi, Matt.

MATT: Hi. Yes. I'm just calling - I'm a professional pilot myself. And one of the biggest problems that we have is when people have their headsets or their cell phones and electronic devices on, it actually comes through our headset, and it creates a lot of problems for us hearing air traffic control, whereas until we're at 10,000 feet, we are told not to talk amongst ourselves. That's myself and the co-pilot.

FLATOW: And you think that's why that rule is there.

MATT: Yeah.

BILTON: Yeah. Well, I mean, I think that one of the things is that - the - it's like you just said, you know, people are lumping everything together. And the reality is I don't - I can't find anyone that really just wants to be able to talk on their cell phone during takeoff and landing. But I've spoken to hundreds of people that want to be able to read an e-book, and those devices are not transmitting anything to the cockpit or anything. And you can see that by the fact that American Airlines has approved that the pilots actually use these devices during take off and landing. They're not shutting them down until they reach 10,000 feet. They're on the entire time.

FLATOW: All right, Nick. Thank you, Nick. Thank you, Brian. Nick Bilton is the lead writer of the Bits blog and columnist of The New York Times. Brian Clegg, science writer and author of "Inflight Science: A Guide to the World from Your Airplane Window." Thank you, gentlemen, for joining us. And happy holidays to you.